Towards EEW in Central America

Abstract

Central America has a very high exposure to seismic risk. In particular, moderate on-shore and tsunamegenic off-shore seismicity can induce strong motions along the heavily populated Central American Pacific coast. Though improving the building stock is the best way to mitigate the earthquake hazard, earthquake early warning has the potential to provide some warning of impending strong motion, and can be part of wider program to reduce losses during future earthquakes. At minimum, accurate estimates of ground motions provided contemporaneously with shaking can also provide invaluable information to authorities and populations if cascading failures in communications and power occur. Following an initial feasibility study with INETER in Nicaragua, that included developing a prototype system which has been providing alerts to INETER since 2016, the SED is collaborating with monitoring agencies across the region to develop the capacity for EEW. Central America has is a long-standing tradition of sharing data and best practice across borders, and most networks already operate well-configured SeisComP3 automated processing systems. This means that it is relatively easy to setup demonstration systems using the Virtual Seismologist and Finite-Fault Rupture Detector algorithms that the SED has been developing over the last decade. Limited resources and challenging operational conditions mean that target alerts times under 10s that can be reached in other countries are currently not realistic in this region. However, for earthquakes occurring near the shore, alerts with accurate locations and magnitudes are routinely obtained within 20s of origin time, and this can be improved. In this presentation we present the project and describe how we propose to build EEW capacity. In particular, the seismic networks need to implement a medium term strategy that prioritises EEW – hardening infrastructure and reducing latency. Most importantly, densification of the network with appropriate strong motion sensors in key areas is required. Key features for new instrumentation are low cost and robustness. We will also show how we are testing candidate sensors, and estimating their EEW potential, in order to build the densest effective EEW infrastructure with limited funding.